In certain petrochemical reactions the use of catalysts containing metal impregnated pores having diameters less than about 100 .ANG. can present many problems. Diffusional limitations can occur when reactions take place in very small pores. Plugging of fine pores can occur by deposition of polymers, tars or other coking material. Many petrochemical feedstocks contain various metal impurities such as nickel, vanadium or ion which can deposit out and poison small pores sized catalyst materials.
U.S. Pat. No. 4,356,113, issued Oct. 26, 1982, teaches a method for producing catalyst substrates containing pores within a certain calibrated range (100-1550 .ANG.) by incorporating carbon black particles into an alumina gel and subsequently burning them out during calcination.
U.S. Pat. No. 3,417,028, issued Dec. 17, 1968, discloses a preparation of catalyst supports having increased pore volume in larger pore sizes by incorporating selected polymers into hydrous gels of alumina, silica or alumina-silica prior to calcination.